This invention relates to electrical resistance "spot heaters" and particularly to electrical resistance heaters readily conformable to the shape of an object for localized heating.
Heaters for applying heat to localized areas are generally referred to as "spot heaters". Spot heaters have been found to be particularly useful in heating crankcases of refrigerator compressors to maintain the refrigerant at a predetermined temperature to prevent "slugging" of the refrigerant caused by its increased viscosity. Spot heaters which are placed in contact with the object to be heated may be of a flexible or rigid construction. Such contact spot heaters of a rigid construction (exemplified by that disclosed in U.S. Pat. No. 3,500,444 to Heese et al) are, of course, unsuitable for heating objects having various surface contours since such heaters conform to only a single contour. While pliable spot heaters have been disclosed in U.S. Pat. Nos. 2,052,614 and 1,632,651, these employ heating elements or wires wholly encapsulated within a moisture-proof material of molded rubber or other thermal insulating material. Such heaters are inefficient from the standpoint of heat transfer because the moisture-proof sealing materials in which the heating elements are encapsulated are invariably a good thermal insulation. In addition, such heaters are expensive to manufacture because of the high materials costs of the moisture sealing material used to fully encapsulate the heating element.
Accordingly, it is a principal object of the present invention to provide a spot heater construction which overcomes the drawbacks of the prior art.
It is another object of the present invention to provide a unidirectional heater construction which is relatively simple and economical to manufacture, can be readily installed for heating objects of various contours and which is efficient in operation.
It is a further object of this invention to provide a spot heater composed of separately fabricated individual components which lend themselves to simple assembly procedures.
Still another object of this invention is to provide a highly versatile heater construction of the above type in which the specifications of each component may be separately selected and the components assembled in various combinations thereby providing a highly versatile and economical method of fabricating heaters of maximum efficiency for each particular utility without the necessity of maintaining large inventories of completed heater units.